High-pressure decorative laminates have been widely employed in the building industry as counter and furniture tops. Because they are resistant to scratching and various liquids and heat, the high-pressure decorative laminates have been popular in the furniture industry, where they not only provide an attractive appearance matching adjacent natural wood finishes, but also a surface more durable than wood.
In the production of such counter and furniture tops, particularly the latter, it is necessary to cut or otherwise machine the top to the desired dimensions and configuration. This may be accomplished by simultaneously machining a stack of laminates which are thereafter individually bonded to a rigid structural base member to form a furniture assembly, or by first bonding a laminate sheet to a rigid base member of substantial thickness and then machining the composite assembly. Irrespective of the method, the laminate must be machine cut to form rounded corners etc.
The hard durable surface provided by the laminate is relatively difficult to machine, and tungsten carbide-tipped tools are frequently employed to reduce tool wear and minimize the down-time involved in sharpening tools. Machinability and tool wear are, accordingly, particularly important factors in the use of high-pressure decorative laminates for counter and furniture tops.
One solution to the problem of tool wear is described by Palazzolo and McCaskey in U.S. Pat. No. 3,940,538. There, a high yield, saturable, wood fiber core paper was produced containing at least 65% hardwood fibers, containing 8 to 15% total lignin content. Up to 35% softwood fibers could be present, but with softwood lignin contents not greater than 2.8%.
Applicants have discovered that the use of random felted cotton linter fiber paper, as a complete substitute for wood fiber paper, provides even further improvement in terms of non-abrasiveness and tool wear.
Cotton batting, unwoven webbing and fabric have been suggested as a phenolic resin impregnated core material for various types of high pressure decorative and electrical grade laminates by Dickey, in U.S. Pat. No. 1,352,436, Hickler, in U.S. Pat. No. 2,456,006 and Boiney et al, in U.S. Pat. No. 3,013,916, respectively. None of these patents, however, have dealt with or solved problems of laminate machining, or recognized that random felted cotton linter fiber paper can be a complete non-abrasive substitute for wood fiber paper, to improve the machinability of high pressure decorative laminates.